1. Field of the Invention
The present invention relates to a water jet propulsion boat equipped with a fuel pressure detection unit arranged to detect the pressure of fuel delivered from a fuel tank to an engine by a fuel pump.
2. Description of the Related Art
Conventional water jet propulsion boats are equipped with a fuel pressure detection unit for detecting the pressure of fuel delivered from a fuel tank to an engine by a fuel pump (for example, see JP-A-2002-161800). In this conventional water jet propulsion boat, the fuel pump is mounted inside of the fuel tank, which is provided in an engine room of a boat body. When an electrical system of the engine starts, the fuel pump is activated and delivers fuel from the fuel tank to the engine by pressurizing the fuel. A fuel pressure sensor for detecting the fuel pressure is provided on a pipe connecting the fuel tank to the engine, and the fuel tank is provided with a pressure adjustment valve for stabilizing the pressure of the fuel delivered from the fuel tank to the engine. Thus, the fuel in the fuel tank can be delivered to the engine at a constant pressure adjusted by the pressure adjustment valve, and the pressure of the fuel delivered to the engine is detected by the fuel pressure sensor.
However, in the conventional water jet propulsion boat, the fuel pump is driven continuously while the engine is running in order to deliver fuel to the engine. When the engine stops, the fuel pump also stops. Because the fuel pump keeps driving while the engine is running, a large amount of power is consumed, and thus, a large size battery is required. In addition, this arrangement also shortens the life of the fuel pump. There is also the problem of the increased cost due to the installation of the pressure adjustment valve for stabilizing the pressure of the fuel delivered from the fuel tank to the engine. Furthermore, because a fuel inlet is positioned in an upper portion of the fuel pump, air enters the engine due to operation of the fuel pump when the water jet propulsion boat has overturned. Consequently, the ability of the engine to restart is decreased. Because of this, it is not desirable to continuously drive the fuel pump when a water jet propulsion boat has overturned.